In the specification of French granted patent FR 2 655 095B1, it was proposed that two components should be assembled together by preforming on a female member at least one groove portion defining a concavity which was oriented radially beside the shoulder of the female member, the groove portion being circumferentially elongated. A male member was then applied against the shoulder of the female member, and was subjected to working such that some of the material of the male member was caused to invade at least part of the groove portion in the female member in plastic flow.
In the above mentioned French patent, the groove portion in the female member extended beside the periphery of the shoulder having the larger diameter, the shoulder being generally annular in shape so that the said periphery was its outer periphery; and the concavity of the profile of the groove portion was oriented radially away from the axis of the assembly (i.e. the common axis of the two components once they were assembled together). That arrangement is such that the plastic flow of the material of the male member into the groove portion or portions takes place radially inwardly, i.e. away from the said periphery of the shoulder and towards the common axis. The female member is therefore provided with a plurality of elongated groove portions disposed from place to place circumferentially and alternating with axially elongated grooves; the working of the male member is performed in such a way that its material invades at least part of each said groove portion and at least part of each axially elongated groove, in plastic flow.
That method of assembly is satisfactory in numerous applications, especially when the assembly is to constitute a friction plate of a clutch, or a pulley of a speed varying device, in particular for a motor vehicle. The method is, as will be clear from the foregoing, carried out on the smaller, or inner, periphery of the male member concerned. However, such a method is not normally suitable for making the primary part of a torsion damper, in particular for a motor vehicle, especially in the case in which some degree of sealing has to be provided in the resulting assembly. The reason for this is partly that it would then be necessary to carry out the working or upsetting operation on the larger or outer periphery of the male member.